Largest Maplestory hacking website being sued by Nexon America and Nexon Korea Corp.

In this case, the prosecution will be helped by the fact the the defendant is selling the knife directly to a known criminal knowing fully well what the criminal intends to do with the knife.

Somewhat beside the point though, the defense will still have to try that argument since the role of defense is to defend, regardless of the guilt of their client.
Were it not being specifically marketed for indefensible purposes they defense would have a better chance, yes.